Dust cap



July 6,1926.

H. P. KRAFT DUST CAP ori imnj Filed Oct 14. 1918 INVENTOR w, ATTORNEYS nethod of constructing the cap isv more ap- .plicable .to easily drawn metal, such as'brass. -lVhen applied to iron Or steel, for instance, greater diiiiculties are. encountered due to patent da i. I'T QS.TA T E5? HENRY r. KRAFT, orninenwoon, NEW JERSEY;.EDGAR J; amplifies ANDQEABIJ A. s; mum nxnoorons or SAID HENRY nxnnr'r, nncnasnn.

nUsr can Application filed October -14, i918,.s ia1 m. a5s,o771 renewed May 20,1 25.

1 This invention relates to dustv capsfor tire valves, and aims to'provide certain improve- .mentsftherein, I r

. As CuStOIIlfiI'llYID'MlG,.dUSt'CELPS are drawn from" sheetmetal blank by a successionof cuppingope'rations which graduallydeepen the blankinto properform'., "This process.

' requires repeated annealing which also adds to its expense, and the total time v required to complete the cap. 'Furthermore,}thi's excessive wear on the tools, etc.

According to the present invention, I aim to provide a dust caplin which these various disadvantages will be obviated. To this end I construct a cap whichis formed of a fiat. sheetmetal blank preferably without draw-' ing operations, or if such operations are emeasily effected. In practising the invention according to the preferred form, I' take a ployed, I limit them to those whichlare fiat blank'and stamp it into suitable shape, and then roll it or form it into cylindrical shape, and closethe end thereof by bending themetal of the endof the cylinder. The invention includes certain. other improvements which will be hereinafter more fully described. a i

In the drawings, wherein I have illustrated several forms of the invention,-

7 cap.

Figure 1 is a plan of a sheet metal blank adapted for the construction of one form of ap i v Fig.2is a top edge viewithereof.

Fig. 3 isasidefview of a partially closed blank. i, I

' Fig. 4: is a top view of Fig. 53. V

Fig. 5 is an elevation of the completed Fig. 6 isa top view of Fig. 5.

pleted.

Y Fig.8.

"- 1 -Fig. 10 is a sectional view of Fig.9 on

an enlarged scale.

Fig. 11 is a sectional view on a similar scale ofa modification of Fig. 10.

Fig. 7 is a blank adapted for a modifiedThe cap may Fig. 9 is a sectio'n on the lineg99 in Referring first to Figs. 1 to 6, let' A indi cate a suitable blank of sheet metal such as sheet brass, iron or. steel. .YBy the use of a j proper punch; this'is formed preferably in one operation from .a flatfpiece of metal.

As showninFig. 1,' the topiofthe blank is "provided with; a number of pointed projectionsiB. [Thesefmaybefour in number, as

show nlor' a-less or. greater number,if desired. Atone' sidexof the blank is' formed .a series of dove-tailed recesses C, andon'ithe other side a series of similarly shaped projections j D'. I

to leave one ofthe'lugs' E of the Urshaped body longer than the other F, as .shown'in' Fig. 4. .The cap'is then preferably placed upon a cylindrical mandrel and the two 'edgesE andfF rolled down, the edgeFbe-i ing rolled slightly in advance'of the edge E, so that the projections D may enter the re-f q p cesses laterally. If it is desiredthatjthe cap shall be screw-threaded at its bottom, it

may then be rolled or spun, as shown'atG,

" to reduce its diameter at its foot. The projections B are then bent down "toward-each other until the endiof'the cap is closed as best seen in Fig/G/ The precise character of these projections depends upon the shape V which is to begiven toithe closed'end of the cap. Where four projectio'ns are used, and

Y the'end of the cap is tobe dome-shaped, the curved and pointedshape' indicated in Fig. l is-best employed. Therestrictedlfortion G may then be tapped'as shown a' The construction thus described produces a cap in' which'the edges are interlocked so -asfto prevent lateral separation. Ifdesired,

: the interlocked edges may be given a con-.

siderable' amountof pressure so as to. ex-

way,-su'ch as y nickel-plating it or the. like.

E In the modification illustrated in Figs. 7

to 10 a blank 'J is bestemployed which .is

similar 'to the blank A of Fig. 1, with the exception that the interlocking projections areomittedQ This blank isflthen rolled to 1 J05 cylindrical form and its end closed as in the preceding figures. In some-casesthe ..cap. will resist lateral separation sufficiently I torender it unnecessary to ,prov1de any pandthem laterallysomewhatto increase the security of the grip upon each other.

be finished "in any :suitable;

other means to hold the edges together. I

prefer, ghojvever, to provide a means for this purpose, and in the drawing I have shown one of such means. By reference to Figure 10, it will be seen ii-hat the formation of a reduced portion or n'e'ok'K which is adapted to receive the screw-thread is usually accom-' panied by the formation of an external groove. In Figs. 9 and 10 I have shown a means for providing against lateral separat on comprismg ,a collar or sleeve L set n suchgroove .and preferably 10f such thickness as to be substantially flush with the exterior of therap This collar is preferably applied a ferrulin r', machine which reduces its-body uniformly Without corrugating .it, so that the collar presents a smooth and gfinished exterior, ItV is preferable to apply the collarahefore the/tapping opera- {tion "In the construction of .Figs. 1 to 10 the is formed with afrbottom. flange M or M; In Figz ll the flange is formed upon the collar Lflandthe metal of the cap is spun or turned over: slightly at the bottom to -c nfine the .collar L V in place.

The edges of the cap ,may' be united in ,any suitable manner, if desired, in addition to orin jlieuio-f the sleeve.

'glhe cla med nvention may recelve other embodiments than those herein specifically illustrated and described. 7 r

WVhat- I claim is a 1.. A dust cap comprising a structure formed of a flat sheet-metal-blankLbent into cylindrical form with its longitudinal edges in abutting relation, and having a closed top integrally formed fromsaid blank,and

an QnCirQlingmember surrounding the cap tor preventlng separation of the abutting edges thereof.

2, rhdustv cap comprising a" sheet metal body bent to cylindrical form, having an open end, an endless annulus around said annulus and outturned flange strengthenlab cylindrical body adjacent its open end, and. an out-turned flange at said open end, said ing said body andproviding a broad bear- In witness whereof, I have ,hereunto -s1 gned my nai ne.

HENRY 1 KRAFT, 

